NIST 800-171 Rev 3

Overview

NIST Special Publication 800-171 Revision 3 provides requirements for protecting Controlled Unclassified Information (CUI) when it resides in nonfederal systems and organizations. This framework is critical for government contractors and organizations that handle sensitive federal information. Nabla’s automated assessment analyzes your infrastructure-as-code to evaluate compliance against the 110+ security requirements in NIST 800-171 Rev 3.

Framework Details

Framework: NIST 800-171
Version: Revision 3
Control Count: 110+ requirements across 14 families
Output Format: OSCAL Assessment Results (JSON)
Primary Use Case: CUI protection, government contracting (DFARS compliance)

Assessed Control Families

3.1 Access Control

Control	Title	Assessment Method
3.1.1	Limit system access to authorized users	Detects IAM users, roles, RBAC resources
3.1.2	Limit access to types of transactions	Evaluates IAM policies and access controls
3.1.3	Control CUI flow	Analyzes network segmentation and security groups
3.1.5	Employ least privilege	Identifies wildcard permissions in policies
3.1.12	Monitor remote access sessions	Detects VPN gateways and remote access controls
3.1.13	Cryptographic mechanisms for remote access	Verifies TLS/encryption for remote connections
3.1.14	Route remote access via managed access control points	Checks for VPN/bastion architectures
3.1.20	External system connections	Identifies VPC peering, transit gateways

3.3 Audit and Accountability

Control	Title	Assessment Method
3.3.1	Create and retain system audit logs	Detects CloudTrail, CloudWatch, diagnostic settings
3.3.2	Alert on audit logging process failure	Identifies CloudWatch alarms, monitoring alerts
3.3.4	Review and update logged events	Verifies configurable audit mechanisms

3.4 Configuration Management

Control	Title	Assessment Method
3.4.1	Establish baseline configurations	Infrastructure-as-code represents versioned baselines
3.4.2	Enforce security configuration settings	Detects version-controlled configuration
3.4.6	Employ least functionality	Identifies unnecessary exposed services/ports
3.4.7	Restrict network access	Evaluates security groups and firewall rules

3.5 Identification and Authentication

Control	Title	Assessment Method
3.5.1	Identify system users	Detects IAM users, Azure AD, identity platforms
3.5.2	Authenticate users and devices	Analyzes authentication mechanisms
3.5.3	Use multifactor authentication	Verifies MFA requirements in Cognito, IAM policies
3.5.7	Prevent reuse of identifiers	Validates cloud IAM service enforcement
3.5.10	Store and transmit credentials securely	Detects Secrets Manager, Key Vault, Secret Manager

3.11 Risk Assessment

Control	Title	Assessment Method
3.11.1	Conduct risk assessments	Organizational process (not fully assessable via IaC)
3.11.2	Scan for vulnerabilities	Detects AWS Inspector, Security Center, vulnerability scanning

3.13 System and Communications Protection

Control	Title	Assessment Method
3.13.1	Monitor and control communications at boundaries	Identifies security groups, NACLs, firewalls, WAF
3.13.5	Implement subnetworks for public components	Verifies subnet separation
3.13.8	Cryptographic mechanisms for transmission	Detects HTTPS listeners, TLS configurations
3.13.10	Cryptographic key establishment and management	Analyzes KMS, Key Vault, key rotation
3.13.11	Employ FIPS-validated cryptography	Verifies use of FIPS 140-2 validated services

3.14 System and Information Integrity

Control	Title	Assessment Method
3.14.1	Identify and manage system flaws	Organizational process (patch management)
3.14.2	Provide protection from malicious code	Detects GuardDuty and malware protection
3.14.3	Monitor system security alerts	Identifies SNS topics, monitoring alerts
3.14.6	Monitor organizational systems	Detects comprehensive logging and monitoring
3.14.7	Identify unauthorized use	Analyzes GuardDuty, Security Hub, threat detection

Multi-Cloud Support

Expanding Beyond AWS: While our initial implementation focuses on AWS resources, we’re actively adding support for:

Azure: azurerm_* resources (Key Vault, RBAC, NSGs, Sentinel)
Google Cloud: google_* resources (Cloud KMS, IAM, VPC, Security Command Center)
Multi-Cloud: Unified compliance posture across hybrid environments

The NIST 800-171 assessor already includes detection for Azure and GCP resource types. Coverage will continue to expand based on customer needs.

Currently Supported Resource Types

AWS Resources

aws_iam_user, aws_iam_role, aws_iam_group, aws_iam_policy
aws_security_group, aws_network_acl, aws_vpc, aws_subnet
aws_cloudtrail, aws_cloudwatch_log_group, aws_cloudwatch_metric_alarm
aws_kms_key, aws_kms_alias
aws_s3_bucket (with encryption checks)
aws_db_instance, aws_rds_cluster (encryption at rest)
aws_vpn_gateway, aws_vpn_connection, aws_customer_gateway
aws_cognito_user_pool
aws_secretsmanager_secret, aws_ssm_parameter
aws_guardduty_detector, aws_inspector_assessment_template
aws_lb_listener, aws_alb_listener

Azure Resources (Coming Soon!)

azurerm_role_assignment, azurerm_role_definition
azurerm_network_security_group, azurerm_subnet, azurerm_firewall
azurerm_monitor_diagnostic_setting, azurerm_monitor_metric_alert
azurerm_key_vault, azurerm_key_vault_key, azurerm_key_vault_secret
azurerm_active_directory_user
azurerm_virtual_network_gateway, azurerm_virtual_network_peering
azurerm_security_center_subscription_pricing
azurerm_policy_definition, azurerm_policy_assignment

Assessment Workflow

OSCAL Output Structure

Results conform to OSCAL 1.0.4 Assessment Results format:

{
  "assessment-results": {
    "uuid": "assessment-uuid",
    "metadata": {
      "title": "Nabla NIST 800-171 Assessment",
      "version": "1.0.0",
      "oscal-version": "1.0.4"
    },
    "results": [{
      "uuid": "result-uuid",
      "title": "NIST 800-171 IaC Assessment",
      "description": "Automated assessment results from Terraform statefile analysis",
      "start": "2025-10-05T12:00:00Z",
      "end": "2025-10-05T12:05:00Z",
      "local-definitions": {
        "components": [...],
        "inventory-items": [...]
      },
      "observations": [
        {
          "uuid": "obs-uuid",
          "title": "3.1.1 Evidence",
          "description": "Identity resource: aws_iam_user.admin",
          "methods": ["TEST"],
          "subjects": [{
            "subject-id": "component-uuid",
            "type": "component"
          }],
          "props": [
            { "name": "control-id", "value": "3.1.1" },
            { "name": "status", "value": "satisfied" },
            { "name": "automated", "value": "true" }
          ]
        }
      ],
      "findings": [
        {
          "uuid": "finding-uuid",
          "title": "3.1.5 Finding",
          "description": "Overly permissive wildcard (*) found in policy",
          "target": {
            "target-id": "3.1.5",
            "type": "control"
          },
          "related-observations": [
            { "observation-uuid": "obs-uuid" }
          ]
        }
      ],
      "reviewed-controls": {
        "control-selections": [{
          "include-controls": [
            { "control-id": "3.1.1" },
            { "control-id": "3.1.2" }
          ],
          "source": {
            "href": "https://csrc.nist.gov/publications/detail/sp/800-171/rev-3/final"
          }
        }]
      }
    }]
  }
}

Example Assessment Request

curl --request POST \
  --url https://api.usenabla.com/v1/cmmc \
  --header 'Content-Type: application/json' \
  --header 'X-Customer-Key: <x-customer-key>' \
  --data '{
  "name": "<string>",
  "format": "oscal",
  "source_type": "terraform_state",
  "source_content": "<string>",
}'

Common Findings

High-Severity Issues

3.1.5 - Overly Permissive Policies

Finding: "Overly permissive wildcard (*) found in AWS IAM Policy"
Remediation: Replace wildcards with specific resources and actions

3.5.3 - Missing MFA

Finding: "No multifactor authentication found in infrastructure"
Remediation: Enable MFA requirements in Cognito user pools or IAM policies

3.13.11 - Non-FIPS Cryptography

Finding: "No FIPS-validated cryptographic modules found"
Remediation: Use AWS KMS, Azure Key Vault, or GCP Cloud KMS

Medium-Severity Issues

3.3.1 - Insufficient Logging

Finding: "No event logging mechanisms found"
Remediation: Enable CloudTrail, VPC Flow Logs, and application logging

3.13.8 - Unencrypted Transmission

Finding: "No cryptographic mechanisms found for data in transit"
Remediation: Configure HTTPS/TLS on load balancers and API endpoints

DFARS Compliance

NIST 800-171 compliance is required for:

Defense Federal Acquisition Regulation Supplement (DFARS) clause 252.204-7012
Organizations that process, store, or transmit Controlled Unclassified Information (CUI)
DoD contractors and subcontractors

This automated assessment helps demonstrate compliance with DFARS requirements, but should be supplemented with:

System Security Plans (SSP)
Plan of Action & Milestones (POA&M)
Certification from C3PAO (Cyber AB)

Limitations

Important Assessment Limitations:

IaC-Only: Only evaluates resources defined in infrastructure code
Runtime Gaps: Cannot assess operational security practices, user behavior, or physical security
Organizational Controls: Many 800-171 requirements involve policies, procedures, and training
Partial Coverage: Some controls (3.1.14, 3.11.1, 3.14.1) require organizational assessment
Cloud Provider Trust: Assumes FIPS validation claims by AWS/Azure/GCP are accurate

Best Practices

Layered Assessment: Combine automated IaC scanning with manual policy review
Continuous Monitoring: Run assessments on every infrastructure change
Evidence Retention: Store OSCAL outputs for audit trail and POA&M tracking
Gap Analysis: Use findings to prioritize remediation efforts
Third-Party Validation: Consider C3PAO assessment for official certification

Scoring and POA&M

While Nabla provides automated control assessment, official NIST 800-171 scoring requires:

Basic (0-9 points per control)
Derived (additive scoring)
Plan of Action & Milestones for deficiencies

Use the assessment findings to populate your POA&M:

{
  "control": "3.5.3",
  "finding": "No MFA enforcement",
  "risk_level": "High",
  "remediation_plan": "Implement MFA for all privileged accounts",
  "completion_date": "2025-12-31"
}

NIST 800-53 - Comprehensive security controls catalog
NIST 800-172 - Enhanced protection requirements
FIPS 140-3 - Cryptographic module validation
CMMC 2.0 - Cybersecurity Maturity Model Certification

API documentation

Control Mapping Schemas

Evidence

Firmware

FIPS

Overview

Framework Details

Assessed Control Families

3.1 Access Control

3.3 Audit and Accountability

3.4 Configuration Management

3.5 Identification and Authentication

3.11 Risk Assessment

3.13 System and Communications Protection

3.14 System and Information Integrity

Multi-Cloud Support

Currently Supported Resource Types

Assessment Workflow

OSCAL Output Structure

Example Assessment Request

Common Findings

High-Severity Issues

Medium-Severity Issues

DFARS Compliance

Limitations

Best Practices

Scoring and POA&M

References

​Overview

​Framework Details

​Assessed Control Families

​3.1 Access Control

​3.3 Audit and Accountability

​3.4 Configuration Management

​3.5 Identification and Authentication

​3.11 Risk Assessment

​3.13 System and Communications Protection

​3.14 System and Information Integrity

​Multi-Cloud Support

​Currently Supported Resource Types

​Assessment Workflow

​OSCAL Output Structure

​Example Assessment Request

​Common Findings

​High-Severity Issues

​Medium-Severity Issues

​DFARS Compliance

​Limitations

​Best Practices

​Scoring and POA&M

​Related Frameworks

​References

Overview

Framework Details

Assessed Control Families

3.1 Access Control

3.3 Audit and Accountability

3.4 Configuration Management

3.5 Identification and Authentication

3.11 Risk Assessment

3.13 System and Communications Protection

3.14 System and Information Integrity

Multi-Cloud Support

Currently Supported Resource Types

Assessment Workflow

OSCAL Output Structure

Example Assessment Request

Common Findings

High-Severity Issues

Medium-Severity Issues

DFARS Compliance

Limitations

Best Practices

Scoring and POA&M

Related Frameworks

References